Blunted rise in platelet count in critically ill patients is associated with worse outcome

OBJECTIVETo test the hypothesis that a low rate of change of platelet counts (PCs) after admission to the intensive care unit (ICU) is associated with mortality. Low PCs are known to be associated with disease severity in critically ill patients, but the relevance of time-dependent changes of PCs has not been investigated. DESIGNRetrospective study. SETTINGA 12-bed surgical ICU of a university hospital. PATIENTSAll adult patients admitted to the ICU for at least 4 days during a 7-yr period. INTERVENTIONSAt admission, Acute Physiology and Chronic Health Evaluation scores were calculated. PCs and leukocyte counts were analyzed from admission to day 10. The daily rise of the PCs (ΔPC/Δt) from day 2 to day 10 was calculated. Rates for 30-day mortality as well as hospital mortality were determined. MEASUREMENTS AND MAIN RESULTSA total of 1415 admissions were studied. Median PCs (interquartile range) initially decreased and subsequently increased, with a higher PC in 1203 survivors than in 212 nonsurvivors from day 2 onward (302 [range,181–438]·10/mm/day vs. 129 [range, 62–228]·10/mm at day 10;p < 0.001). After stratification of patients per type of surgery, within each group PC was also higher in survivors. Mean ΔPC/Δt was more than five times higher in survivors compared with nonsurvivors30 ± 46·10/mm/day vs. 6 ± 28·10/mm/day (p < 0.001). The area under the receiving operating characteristic curve of ΔPC/Δt for 30-day survival was 0.743 compared with 0.728 for the Acute Physiology and Chronic Health Evaluation. Leukocyte counts showed marginal differences between nonsurvivors and survivors. CONCLUSIONA blunted or absent rise in PCs in critically ill patients is associated with increased mortality. ΔPC/Δt is a readily available and simple parameter to improve assessment of critically ill patients.